The scenario was shared to Reddit by the father's new partner, who asked for advice on what she said was a "stupid" arrangement.
She revealed that she was now engaged to this man and questioning her commitment due to his stance.
She said he had a "hostile" split with his ex before their daughter was born and was "furious" at the name she chose.
Although he was able to convince his ex to allow the child to have his surname, she wouldn't relent on choosing her first names.
"My fiance and his family have decided that since she is now too old to go back to court on this again, the answer to this is for this child to have a 'mom's house' name and a 'dad's house' name," she wrote.
Saying that she believes that the 2-year-old's dual names are "ridiculous", she admitted that she was doubting the future of her relationship with the angry dad.
"I don't want any part in this," she wrote.
"I don't think it will even work because this kid is already going to be 3 years old sooner rather than later, it will make me look like the toxic stepmother, and it's just stupid to have a kid going by two completely different names. She's one person."
Commenters on Reddit were unequivocal in their stance.
"Your fiance is a petty man. Personally, I would never have made it to engagement with such a person. This is what you have to look forward to when your relationship/marriage ends," one person wrote.
Another said: "A man who views a child, a small person, as a pawn and a trophy. He apparently doesn't care that this will be incredibly confusing for the child. He just wants his own way. He is a terrible father already."
